The book explores the constitutional and genetic basis of human body-build, distinguishing between ontogenetic changes during growth and adult weight variations at a fixed stature. The author addresses whether physical differences stem purely from diet and activity or from inherited physiological factors. To measure build quantitatively, the ratio of weight to the square of stature is adopted as a standard index, dividing human variation into five distinct classes ranging from very slender to very fleshy. Through extensive mass studies and family pedigrees, the inheritance patterns of these builds are analyzed.
The findings reveal that fleshy traits show partial dominance over slenderness, and progeny of selected parents exhibit regression toward mediocrity. The analysis of special matings demonstrates that slender parents generally carry recessive factors and yield less variable offspring, whereas fleshy parents produce more variable progeny due to heterozygous genetic combinations. The study also investigates the correlation between specific physical builds and the incidence of various diseases during youth and middle age. Ultimately, the work concludes that variations in human body-build are primarily driven by hereditary idiosyncrasies of metabolism and development, modulated by endocrine functions and environmental factors.
